1. Field of Invention
This invention relates to a timing generator which is capable of delaying its input timing signal in such a way that the delay time can be set with high accuracy and high resolution.
2. Description of the Prior Art
In the prior art, timing generators have been used to accurately determine the timing of measurements being made, for example, by systems for inspecting digital LSIs. FIG. 1 is a waveform diagram illustrating operation of a first type of conventional timing generator which converts incoming digital values into corresponding analog output V.sub.in, and compare such analog output with a ramp waveform a to obtain a delay time t.sub.d. A second type of conventional timing generator selects several of a number of delay gates.
In the first type of conventional timing generator, the ramp waveform must be linear. Also, a high quality capacitor is needed. The repetition frequency is limited by the ramp waveform. Furthermore, the circuit configuration is complex because a high speed digital to analog converter is required.
The second type of conventional timing generator has a large scale configuration . With this type of timing generator, it is necessary to make uniform the differences between the successively switched delay amounts. It is difficult to obtain good linearity and monotonicity.